This invention relates to a process for preparing coupled aromatic compounds.
Coupled aromatic compounds such as diphenyl methane and methyl-substituted diphenyl methanes are useful as intermediates for the preparation of anthraquinones which are generally useful as dye intermediates and pulping catalysts.
Anthraquinone has been allegedly prepared by the use of diluted toluene in air (1.2 percent). See, for example, Japan Kokai Nos. 1982-24323 and 1983-121238. Such known processes to prepare anthraquinone by direct toluene oxidation can be generally inefficient. Loss of valuable reactant materials through complete combustion to carbon dioxide can be particularly problematical.
In view of the problems with prior art processes for producing anthraquinones and their precursors, it would be highly desirable to provide a new process for preparing anthraquinones and/or their precursors in high yield.